Arcade Fire will be on “Austin City Limits” this Saturday. To promote this, they’ve released a video of themselves playing a sweaty but well-restrained performance of “We Used to Wait” interspersed with behind-the-scenes footage of how the show gets produced. I like the part where we get to see the audience come in: A bunch of friendly-looking music dorks totes psyched to have a good time. Some of them flash the camera what you first think is the devil-ears hand sign. But then you remember that this is Texas, and they’re probably saying “Hook ‘em, ‘Horns!” But R.I.P. Dio, anyway.